Heat transfer device and method of making

ABSTRACT

A heat transfer device and a method of making the same in which the device comprises a heat transfer tube having a longitudinal bore for flow of fluid therethrough, spaced heat transfer internal fins within the tube and distortions in the wall of the tube adjacent the fins that not only distorts the wall but also deflects the fins in the region of the distortions to increase internal fluid turbulence and thereby promote better heat transfer.

United States Patent Inventor Homer D. Huggins Racine, Wis. 812,017

Apr. 1, 1969 Aug. 3. 1971 Modine Manufacturing Company Appl.- No. FiledPatented Assignee HEAT TRANSFER DEVICE AND METHOD OF MAKING 16 Claims,11 Drawing Figs.

us. or 72/367,

29/1573 A, 165/179 Int. Cl 112m 53/06 Field 61 Search 72/367,

[56} References Cited UNITED STATES PATENTS 2.107.031 2/1938 Evans113/118 2,463.997 3/1949 Rodgers .1 165/179 2,905,447 9/1959 Huet165/179 Primary Examiner-Lowell A. Larson Attorney-Hofgren, Wegner,Allen, Stellman & McCord ABSTRACT: A heat transfer device and a methodof making the same in which the device comprises a heat transfer tubehaving a longitudinal bore for flow of fluid therethrough, spaced heattransfer internal fins within the tube and distortions in the wall ofthe tube adjacent the fins that not only distorts the wall but alsodeflects the fins in the region of the distortions to increase internalfluid turbulence and thereby promote better heat transfer.

PATENTEI] AUG 3|97| 3596;495

- sum 1 or 2 INVENTOR HOMER D. HUGGINS av f V mafiM, 1% map! ATTORNEYS.

HEAT TRANSFER DEVICE AND METHOD OF MAKING It is common practice toprovide heat transfer tubes adapted to contain a heat transfer liquidwith these tubes having internalgfins over which the fluid flows forpromoting the heat transfer. These tubes and their integral internalfins are customarily made by extruding, drawing and other methods inwhich the fins and other internal structural details such as webs, whichare types of fins, are smooth and usually continuous andparallel. Thissmooth configuration when the heat transfer fluid is viscous such as anoil operates as extra drag surfaces that permitheavy buildup of.the'viscous boundary layer. In certain instances this buildup canbecome .so severe with viscous fluids that substantially no benefit isexperienced by the additional .internalsurface provided by the fins.

This invention correots'this condition by providing such an internallyfinned tube with external distortions in the regions of the finstodeilect them in the regions of the distortions and thereby increaseinternal turbulence with improved heat transfer.

The invention will be described as. illustrated by the accom panyingdrawings which disclose several different embodiments of the invention.Of the drawings:

FIG. 1 is a side elevational view of an oil cooler tube that iscontacted with a cooling medium for cooling the lubricating oil of aninternal combustion engine.

FIG. 2 is an enlarged cross-stictional .view of the tube of FIG. I takensubstantially along line 2-2 of FIG. 1.

FIG. 3 is a fragmentary sectional view taken substantially along line3-3 of FIG. 2.,

FIG. 4 is a side elevations] view of a heat transfer tube incorporatinga second embodiment of the invention.

FIG. 5 is a sectional view taken ofFIG. 4.

FIG. 6 is a sectional view taken substantially along line 6-6 of FIGS. 4and 5.

FIG. 7 is an enlarged crosswsectional view through an undistorted tubethat may be used in practicing the invention.

FIG. 8 is a view similar to FIG. 7 but showing a further embodiment ofthe invention.

FIG. 9 is a fragmentary plan view of a heat transfer tube embodying theinvention.

FIG. 10 is a view taken substantially along line 10-10 of FIG. 9.

FIG. 11 is a view taken substantially along line 11-11 of FIG. 9.

The method of making the heat transfer device and the heat transferdevice itself are illustrated by the embodiments shown in theaccompanying drawings. Thus. in the first embodiment of FIGS. 1-3 thedevice 1.0 comprises a sinuous tubell carrying on its outer surface theusual fins 12. This tube Ills of oval cross section with parallelopposite walls 13 and 14 connected on the interior by spaced'fins in theform of webs 15 of which only one is shown here. Extending inwardly fromeach wall 13 and Marc internalintegral fins 16 of a different type. Inmanufacturingthe tube II it is initially straight and can be formed byextruding and drawing. Then the tube 11 during the manufacturingoperation is undulated to form in each wall 13 and I4 successive peaksl7 and. valleys 18 with each peak 17 in one wall 13 having acorresponding opposite valley 18 in the other wall 1.4. These successiveundulations form inward distortions which are the spaced valleys 18 inthis embodiment.

In the second embodiment of the invention illustrated in FIGS. 4-6 thetube 21 contains a pair of spaced webs 22 and inwardly extending sets23, 24 and 25 of integral inwardly extending fins withone pair 23 beinglocated on one side of a web 22, the other pair 24 positioned betweenthe spaced webs 22 and the other pair 25 spaced between the oppositeedge of the tube and the adjacent web 22.

In undulating the tube 2.1 in the same manner as the tube 11 of thefirst embodiment. the central pair of fins 24 remain straight while theedge fins 23 and 25 undulate at their peaks,

substantially along line 5-5 as indicated in FIG. 6, to promote'internalturbulence and thus heat. transfer of the fluid flowing past these fins23 and 25. These undulations as shown in FIG. 6 for the outer pair offins 23 and 25 also occur in the fins 16 of the first embodimentof FIGS.ll-3.

In both embodiments the further the fin is from the outer edges 50 ofthe tube, as shown in F IGSJ. 5 and 6, the less distortion there wouldbe in the fins. In fact, in the embodiment of FIGS. 5 and 6, the centralfins 24 as shown in FIG. 6 are substantially undistorted and remainstraight instead of containing the undulations of the outer fins 2 3 and25. The apparent reason for this is that the center channel or duct 51is symmetrical as compared to the two outer channels 52. The two outerchannels are not symmetrical because each is bounded on the sides by theplanar web and the arcuate tube edge 50 while with the center channel 51the sides are defined by the parallel webs 22. Then, when the tube isundulated as shown in FIG. 4 the rounded edges 50 tend to be drawninwardly setting up stresses that cause the outer fins 23 and 25 toundulate. These stresses are not substantially transmitted to thecentral fins 24 so that there is substantially no undulation here.

Because a fin such as the fin 24 that. is a part of a symmetricalchannel does not distort and thus does not undulate the third and fourthembodiments of FIGS. 7 and 8 are provided to illustrate other forms oftubes where undulation is achieved.

The third embodiment of FIG. 7 employs a tube 26 which is undulated inthe same manneras the tube 11 of the first embodiment and 21 of thesecond embodiment. However, the tube here is of different internal andexternal construction. In this embodiment of FIG. 7 the tube is in twoparallel parts interconnected by a central integral wall 27 and prior toundulating the tube 26 each half of the tube on opposite sides of thewall 27is provided with a central web 28 and a pair of fins 29.

Inthe fourth embodiment of FIG. 8 the tube 31 is provided with aplurality. here shown as three, of internal webs 32 that are spaced fromeach other and that extend between the opposite sidewalls 33 and 34 ofthetube 31. Between each pair of webs 32 and between a sidewall and theside of the tube 31 there is provided a fin 35. The edge 36 of each fin35 is curved over.

In the embodiments of FIGS. 7 and 8 the undulating of the tubes 26and 31will cause the free edges 30 and 36 of the fins to contact the oppositetube wall at the peaks and valleys of the undulations. It will alsocause the fins in the nonsymmetrical tube passages or channels toundulate at to the direction of the tube bend as is the case with thefins 23 and 25 of the embodiment illustrated at FIG. 6. Thus, in FIG. 7all fins 29.will undulate while in FIG. 8 only the outer fins 35 willundulate because the more centrally located fins 35 are in sym metricalchannels.

In the fifth embodiment of FIGS. 9-l1 the tube 37 is also provided withopposite sides 38 and 39. These sides in this embodiment areconnected-by a pair of spaced internal webs 40 and between each pair ofwebs and between one web and the adjacent edge of the tube there isprovided a pair of inwardly extending aligned fins 41 formed integrallywith the tube.

In improving the heat transfer turbulence of fluid flowing through thetube of this embodiment each wall 38 and 39 is distorted inwardly byspaced dimples 4'2 and 43 with some 42 being opposite a web 40 andothers 43 opposite a tin 41. The dimples 42cause thecorresponding web 40to bulge laterally as indicated at 44 in FIG. 10. The dimples 43 thatare in the re gion of and opposite the fins 41 cause the fin edges 45 tobe moved closer together in the areas of the dimples 43 as is shown inFIG. 11 and to either touch, remain separated or overlap depending uponthe dimple depth.

I claim:

1. The method of making a heat transfer device; comprising: providing aheat transfer tube having a longitudinal bore for flow of fluidtherethrough and spaced. heat transfer internal fins of preselectedheight with free peaks; and distorting said tube inwardly fromexteriorly thereof in the region of said fins to distort the internalfins laterally, thereby increasing fluid turbulence and promoting betterheat transfer efficiency, said distorting being in a direction parallelto the fin height to distort the fins laterally at said peaks.

2. The method of making a heat transfer device, comprising: providing aheat transfer tube of oval cross section with opposing flat sides havinga longitudinal bore for flow of fluid therethrough and spaced heattransfer internal flns located at said sides and substantially parallelto each other; and distorting said tube inwardly from exteriorly thereofin the region of said fins to distort the internal flns laterally,thereby increasing fluid turbulence and promoting better heat transferefficiency, said distorting providing a series of undulations normal tosaid flat sides.

3. The method of making a heat transfer device, comprising: providing aheat transfer tube having a longitudinal bore for flow of fluidtherethrough and spaced heat transfer internal tins; and distorting saidtube inwardly from exteriorly thereof in the region of said fins todistort the internal fins by providing internally extending spaceddimples in the area of said tins of a depth insufficient to contact theopposite wall.

4. A heat transfer device, comprising: a heat transfer fluid flow tubehaving an internal bore deflned by a wall: a heat transfer internal finextending inwardly of said tube wall for contact by said fluid; andinwardly extending distortion means in the tube wall adjacent said finthat both distorts said wall and deflects said fin in the region of saiddistortion means, thereby improving the heat transfer between theflowing fluid, the tin and the tube wall.

5. The device of claim 4 wherein said tube is of oval cross section withopposite walls extending between opposite tube edges, and there areprovided a plurality of said fins extending providing a heat transfertube having a longitudinal bore for flow of fluid therethrough andspaced heat transfer internal tins; and distorting said tube laterallyinwardly from exteriorly thereof in the region of said tins to provide apermanent inward set in said tube and thereby distort the internal fmslaterally, thereby increasing fluid turbulence and promoting better heattransfer efficiency.

9. The method of claim 2 wherein said distorting is to the degree thatthe internal fin edges adjacent the internally concave portions of theundulations are puckered to provide turbulence undulations. v

10. The method of claim 2 wherein certain of said internal flns extendfrom one of the sidewalls to the other and other flns extend from onewall but terminate in an edge short of the other wall.

11. The method of claim 3 wherein said tube is of oval cross sectionwith opposing flat sides and said internal fins are located at saidsides and are substantially parallel to each other.

12. The method of claim 11 wherein certain of said dimpled distortedfins extend between opposite sidewalls of the tube and others extendfrom one wall but terminate short of the opposite wall.

13. The device of claim 4 wherein there are a plurality of said finsthat extend inwardly of a wall of the tube and comprise free peaksdistorted laterally in undulations.

14. The device of claim 4 wherein said distortions comprise internallyextending spaced dimples in the area of said tins of a depthinsufflclent to contact the opposite wall.

15. The device of claim 4 wherein said tube is of oval cross sectionwith opposing flat sides and said internal fins are located at saidsides and are substantially parallel to each other.

16. The device of claim 4 wherein certain of said dimpleposite wall.

1. The method of making a heat transfer device; comprising: providing aheat transfer tube having a longitudinal bore for flow of fluidtherethrough and spaced heat transfer internal fins of preselectedheight with free peaks; and distorting said tube inwardly fromexteriorly thereof in the region of said fins to distort the internalfins laterally, thereby increasing fluid turbulence and promoting betterheat transfer efficiency, said distorting being in a direction parallelto the fin height to distort the fins laterally at said peaks.
 2. Themethod of making a heat transfer device, comprising: providing a heattransfer tube of oval cross section with opposing flat sides having alongitudinal bore for flow of fluid therethrough and spaced heattransfer internal fins located at said sides and substantially parallelto each other; and distorting said tube inwardly from exteriorly thereofin the region of said fins to distort the internal fins laterally,thereby increasing fluid turbulence and promoting better heat transferefficiency, said distorting providing a series of undulations normal tosaid flat sides.
 3. The method of making a heat transfer device,comprising: providing a heat transfer tube having a longitudinal borefor flow of fluid therethrough and spaced heat transfer internal fins;and distorting said tube inwardly from exteriorly thereof in the regionof said fins to distort the internal fins by providing internallyextending spaced dimples in the area of said fins of a depthinsufficient to contact the opposite wall.
 4. A heat transfer device,comprising: a heat transfer fluid flow tube having an internal boredefined by a wall; a heat transfer internal fin extending inwardly ofsaid tube wall for contact by said fluid; and inwardly extendingdistortion means in the tube wall adjacent said fin that both distortssaid wall and deflects said fin in the region of said distortion means,thereby improving the heat transfer between the flowing fluid, the finand the tube wall.
 5. The device of claim 4 wherein said tube is of ovalcross section with opposite walls extending between opposite tube edges,and there are provided a plurality of said fins extending between saidwalls and extending from one wall but short of the opposite wall.
 6. Thedevice of claim 5 wherein said distortion means comprise a waveundulation at right angles to said opposite walls.
 7. The device ofclaim 5 wherein said distortion means comprises inward dimples in saidwalls each coinciding with a fin.
 8. The method of making a heattransfer device, comprising: providing a heat transfer tube having alongitudinal bore for flow of fluid therethrough and spaced heattransfer internal fins; and distorting said tube laterally inwardly fromexteriorly thereof in the region of said fins to provide a permanentinward set in said tube and thereby distort the internal fins laterally,thereby increasing fluid turbulence and promoting better heat transferefficiency.
 9. The method of claim 2 wherein said distorting is to thedegree that the internal fin edges adjacent the internally concaveportions of the undulations are puckered to provide turbulenceundulations.
 10. The method Of claim 2 wherein certain of said internalfins extend from one of the sidewalls to the other and other fins extendfrom one wall but terminate in an edge short of the other wall.
 11. Themethod of claim 3 wherein said tube is of oval cross section withopposing flat sides and said internal fins are located at said sides andare substantially parallel to each other.
 12. The method of claim 11wherein certain of said dimpled distorted fins extend between oppositesidewalls of the tube and others extend from one wall but terminateshort of the opposite wall.
 13. The device of claim 4 wherein there area plurality of said fins that extend inwardly of a wall of the tube andcomprise free peaks distorted laterally in undulations.
 14. The deviceof claim 4 wherein said distortions comprise internally extending spaceddimples in the area of said fins of a depth insufficient to contact theopposite wall.
 15. The device of claim 4 wherein said tube is of ovalcross section with opposing flat sides and said internal fins arelocated at said sides and are substantially parallel to each other. 16.The device of claim 4 wherein certain of said dimple-distorted finsextend between opposite sidewalls of the tube and others extend from onewall but terminate short of the opposite wall.